best available copx



BEST AVAILABLE COP.

June 1 1926. 1,587,456

w. WOLFF VACUUM TUBE CONNECTION Filed Jan. 31, 1924 IO B l z Z5 Z6 W 0 1 y Fig-Z.

i 33 3/2 L W1 7 A 33 Inventor:

Walther" Wolff;

His Attdornes.

BEST AVAILABLE COP.

Patented June 1, 1926.

UNITED STATES BATENT OFFICE.

WALTHER WOLFF, F KARLSHORST, GERM'ANY, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

VACUUM-TUBE CONNECTION. i

Application filed January 31, 1924, Serial No. 689,717, and in Germany February 9, 1923.

My present invention relates to vacuum tube connections, and more particularly to connections for supplying heating current to the cathodes of vacuum tubes of the thermionic type.

The object of my invention is to provide a connection whereby it will be possible to automatically close the heating circuit for thermionic cathodes of amplifier tubes usedin telephone operation before aconven sation is started over a telephone line, then to-again open the circuit when the conversation is finished.

. Ithas previously been proposed to accomplish this result by means of automatic selective devices such as those employed in automatic telephone service. Such. appa ratus requires numerous switching devices which maybe employed when a large numberof connections are to be made, but are unduly expensive when only a=.small number of;connections is required. :l p

Incarrying my inventioninto effect I provide for: the closing of the heating circuit when ascall is made'over-the-line and for the opening of the heatingcircuit at the close oftheic'onversation' by'sendin'g over the line a: second impulse similar to 'the calling impulse. i ':-'The nove'Lfeatures which lf believe 'to' be characteristic of my inventionare: set-forth with particularity in the appended claims;

My invention' itself, however, will best-be understood by reference to the following de scriptiontaken in: connection with the accompanying drawing inwhich-Figs'l and 2 show respectively two. difierent circuit organizations whereby my invention may be carriedintoe'fiect. v: 1 l.- In? Fig. 1, I have indicated a telephone line F which terminates at the points a and b.- The connection of this lIlDB'LtO tl1B thermionic amplifiers 1 and 2 of any-usual type, which are Y employed for amplifying the conversation sent over the line is omitted as suchconne'ction. forms no part of my invention. Between the points a and b, there is connected the winding of a relay 3, which is adapted to close a. contact at 4. The heating circuit of the cathodes 5 of the amplifiers 1 and 2 comprises the usual battery 6 and the regulating resistance 7. This circuit is brought to the points X and Y.

When a call is sent over the line F relay 3 5 operates to close contact 4. This closes the heating circuit from point Y through contact 4, connection 8, contact 9, connection 10, the windings of relays 11 and 12, to point X. The holding relay 11 then closes contact at i3. so that after the calling current has stopped the heating circuit-remains closed between X and Y, through the windings o't relays 11 and 12 and contact 13. Hence the amplifiers 1 and 2 will remain in their excited condition and conversation over the line can be eii'ected.

In order'to prevent the heating circuit from being opened and closed duringthe continuance of conversation, the retarding relay 1 is provided which permits the open iug-of the'heating circuit only after the end of the conversation and after-a period-:of 5 to seconds has elapsed after the original closing of the circuit. v-

lVhen the: relay 12 is energized-by the closing of the heating circuit, contact is made at 15. This closes a circuit from the positive pole of battery 16 through contact to the winding of relay 14, contact 17, through the connection 18 back to the negative pole of battery 16;After a period of 10-or 15 sec0nds,-'relay'-14 operates, closing contact 19; This closesia circuit from the-positive pole of the battery 16 throughcontact; 15, relay 14:, contact 19, throu thewinding of'relay 20, and .bacir throug li the connection=18 'to .the negative pole of'battery 16: Whemthe relay 20 is energized it breaks contact at 9 and 17, and makes new contacts at 21 and22. By: the breaking-of. contact 17 the circuit for the'retarding relay 14 is interrupted so that the contact is broken at 19. Relay 20, however, remains excited by reason of the circuit which is established from the positive pole of battery 16 through contacts 15, 21', through the-windingof relay 20, and the connection 18v back to the negative pole of battery '16. y

By the operation of relay 20, the system is prepared for the openingof the heating circuit. For this purpose a-special'call is sent over he line F after the termination of the conversation. By this call the relay 3 is again excited, making contact at 4:. By this contact the heating circuit is closed from Y through contact 4, connection 8, contact 22, connection 23, through the winding of relay 12, to the point X. It will be observed that by this operation the circuits are so changed that relay 11 is no longer excited,

consequently the contact at 13 is opened. As soon as thestop'call terminates the relay 3 releases its armature opening contacts at 4; and 22, .thus .opening the heating circuit. Relay 12 is then decnergized and contact is broken at 15,thus deencrgizi-ng the winding of rela 20. Contacts 9 and 17 are thereupon ma e again and the relay system is ready to operate to establish a new connection.

In the connection shown in Fig. 2 the retardin'g relay 14 is omitted. Calling relay 3 in this case has three contacts 24, 25 and 26. When a callis sent over the line the relay 3 is energized and contacts 24 and 26 are made and contact 25 is broken. The heating circuit is then closed from Y through contacts 24 and 27, through the winding of relay 28 to Relay 28now makes contacts at 29, 30,-.sothat after completion of the calling signal the heating circuit remains closed from Y through-contact 29, through the winding. oifi ielayf28' to point X. At the saimetiin contact is established at 25 and a closed from the positive pole of battery '16 through contacts 30 and 25, and winding of reversing relay 31 back to the negative pole of the battery 16. The relay ah-being energized, opens contact 27, and closes contacts at 32 and 33, and thereby putsthe' system in condition for the openingoffthe heating circuit.

-o' efi'ect-the opening of the heating circuit after Econversationis terminated, the closing call is-sen't over the line F Calling relay 3 is, thus excited and contacts again made at 2& and 26.- Current then flows through a circuit from point Y, contact 24, contact 32, and connection 33 'to point X. By this change in the connections the relay 28 is deenergized and hence contacts 29 and 30 are broken. Relay 31, however, remains energized by reason-ofthe circuit established from the positive pole of battery 16 through contact 26, connection 34:, contact 33, through the winding of relay 31, back to the negative pole of battery 16. Hence the contacts 32 and 33 are maintained until the end of the final call. After the linal call has termi mated, contacts 2and 26 are broken and the heating circuit is opened. The circuit of relay 31 is also opened by the opening of contact 26 and the relay system is again ready to operate to establish a new connection. i

' What I'claim as new and desire to secure by Letters Patent of the United States, is

1. The combinationin a telephone system employing a thermionic amplifier, of means responsive to a calling current for closing and opening a heatin'g circuit forthe ampli- Iier cathode.

2. The combination in a telephone system employing a thermionic amplifier, of means responsive to a calling current for closing and opening a heating circuit fort-he amplifier cathode, and means for maintaining the heating circuit closed during the continuance of a conversation.

3. The combination in a telephone system employing a thermionic amplifier, of means responsive to a calling current for closing aheating circuit for the amplifier cathode, means for maintaining the heating circuit closed during the continuance of a conversation, and means responsive to a calling current for opening the heating circuit after the close of a conversation. f

4. The combination in a telephone system employing a thermionic amplifier, of a'relay responsive to a calling current for closing a heating circuit for the amplifier cathode, and means actuated by said relay for maintaining the heating circuit closed when said calling current has ceased to flow and during the continuance 'of a conversation.

5. The combination in a telephone system employing a thermionic amplifier,of a relay responsive to a calling current for closinv' a heating circuit for the amplifier catho iie, and means comprising a; second relay which is actuated by the operation of the first relay I for maintaining the heating'circuit closed when said calling current has ceased to flow and during the continuance of a' conversation.

6. The combination in a telephone system employing a thermionic amplifier, of a relay responsive to a calling current for closing a heating circuit for the amplifier cathode,

means comprising a second relay which is actuated by the operation of the first relay for maintaining the heating circuit closed during the continuance of a conversation, and a third relay which is actuated as a result of the actuation of the first relay and the actuation of which changes the circuit connections to permit the opening of the heating circuit by-a second actuation of the first relay. .Q.

In witness whereof, I have hereunto set my hand this 15th day of January, 1924.

W'ALTHER WOLFF. 

